Utilizing Eqs. (REF ) and (REF ), together with the curvature power spectrum in Fig. REF , we present the gravitational waves density parameter in Fig. REF  for our two sets of parameter values.
The gravitational wave signal of Set 1 is within the reach of future experiments such as LISA [1]}, [2]}, DECIGO [3]}, [4]}, and BBO [5]}, [6]}, [7]}. For Set 2, the signal crosses the sensitivity bound of SKA [8]}, [9]}, [10]} in addition to that of LISA, DECIGO, and BBO.
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